Carbon disulfide is a major industrial chemical, which has a long history of use in the chemical process industries. At one time large quantities of the chemical were used to manufacture viscose rayon, cellophane, and carbon tetrachloride. While these applications have declined, new markets, especially its use as a solvent, show considerable promise.
In the early years of its manufacture, carbon disulfide was produced from charcoal and sulfur at high temperatures in either an electric furnace or a retort. The method was both hazardous and environmentally unsound, but at the time no alternatives were available.
Beginning in the 1960's, a petrochemical process was introduced to manufacture carbon disulfide from natural gas (methane) and sulfur. A great improvement over the old process, this petrochemical technology soon gained dominance. Nevertheless, the petrochemical process was saddled with a major disadvantage: the need to recover sulfur from substantial quantities of byproduct hydrogen sulfide in a Claus unit.
Newer proposals continue to appear for the manufacture of carbon disulfide. One of the most interesting processes was disclosed in U.S. Pat. No. 4,122,156. This process makes carbon disulfide from boiler flue gas by catalytically reducing sulfur dioxide with carbon monoxide to carbonyl sulfide and then converting the carbonyl sulfide to carbon disulfide over an alumina catalyst.
Although this proposal to reduce sulfur dioxide to carbonyl sulfide has considerable merit, the conversion of carbonyl sulfide to carbon disulfide presents certain difficulties. The reaction of carbonyl sulfide to carbon disulfide and carbon dioxide is reversible and does not go to completion under normal conditions. Thus, expensive and inefficient procedures must be employed to get around this limitation.
An object of the present invention is to reduce or eliminate the disadvantages of the prior art in a way which meets the most demanding expectations for safety, environmental responsibility, and efficiency.
These and other objects, features and advantages of the invention will be apparent from the following description and the accompanying drawing.